For certain applications, such as in ranging devices, it is desirable to provide an optical pulse emitter capable of emitting optical pulses of high intensity and short duration. For example, it has been proposed to use a SPAD (Single Photon Avalanche Detector) array to detect the distance to an object in an image scene. This involves transmitting an optical pulse of relatively high intensity and short duration into the image scene, and using the SPAD array to detect a return pulse reflecting off an object present in the image scene. The time of flight of the optical pulse can then be estimated, allowing the distance to the object to be estimated.
A VCSEL (Vertical Cavity Surface-Emitting Laser) is a light emitting device capable of emitting light with an intensity that depends on a level of current driven through it. However, there is a technical problem in providing a circuit capable of driving a VCSEL or similar light emitting device to generate an optical pulse of a relatively high intensity and short duration.